An aspect of the present invention relates to a disk brake comprising a set of brake disks, which comprises a set of rotor disks and a set of stator disks, which are arranged so that every other brake disk consists of or comprises a stator disk and every second disk consists of or comprises a rotor disk, and which are displaceable in relation to one another along a central axis for engagement and disengagement with one another. An aspect of the invention further relates to a planetary transmission and a drive device for a wheel of a vehicle, the device comprising the planetary transmission.
An aspect of the invention relates primarily to the field of work machinery or work vehicles, such as wheel loaders, dumpers (frame-steered vehicles), back diggers (excavator loaders), and excavators.
The drive device therefore comprises the planetary transmission and forms a so-called final drive, or hub-mounted reduction gear. The wheel is then arranged rotationally locked on a hub and the planetary transmission is connected between a drive shaft and the hub. The drive shaft is driven by an angular gear, or center gear, which is in turn driven by the vehicle engine by way of a transmission system.
Arranging a planetary transmission on each drive wheel in this way produces a reduction in rotational speed from the drive shaft to the hub and an increase in torque from the drive shaft to the hub.
Rotationally locking a first set of brake disks to a planet carrier, as disclosed by WO 99/03699, for example, is already known. The brake disks are then connected via splines on a radially outer surface of the planet carrier.
WO 04/104436 describes a planetary transmission in which multiple planet wheel journals are joined by a bolted connection to a common, annular carrier, which has radially outer splines for the first set of brake disks.
It is desirable to provide a disk brake which affords a long service life and which is especially suited for rotationally locking the rotor disks to a journal of a planet carrier in a planetary gear train. In particular it is intended to address the problem of high surface pressures between the journal and the rotor disk.
According to an aspect of the invention, there is a layer of coating material on at least one of the sides of the stator disk for engagement with an adjacent rotor disk.
According to a preferred embodiment the rotor disk is devoid of a layer of coating material on its side. This serves to reduce the losses, so-called splash losses, which occur during the rotation of conventional rotor disks (which have a layer of coating material on both of their lateral surfaces) in an oil bath.
According to a preferred embodiment at least one of the rotor disks has a greater thickness than at least one of the stator disks. The rotating rotor disks are accordingly thicker so as on the one hand to absorb heat energy and on the other to produce a lower surface pressure between the disk and the journal.
The surface pressure between the disk and the journal can consequently be reduced without increasing the overall volume or cost of the brake.
Further advantageous embodiments of the invention are set forth in the following description, in the claims and in the drawings.